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usb: typec: fsa4480: Check if the chip is really there

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Currently, the driver will happily register the switch/mux devices, and
so long as the i2c master doesn't complain, the user would never know
there's something wrong.

Add a device id check (based on [1]) and return -ENODEV if the read
fails or returns nonsense.

Checking the value on a Qualcomm SM6115P-based Lenovo Tab P11 tablet,
the ID mentioned in the datasheet does indeed show up:
 fsa4480 1-0042: Found FSA4480 v1.1 (Vendor ID = 0)

[1] https://www.onsemi.com/pdf/datasheet/fsa4480-d.pdf

Fixes: 1dc246320c ("usb: typec: mux: Add On Semi fsa4480 driver")
Cc: stable <stable@kernel.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Link: https://lore.kernel.org/r/20240729-topic-fs4480_check-v3-1-f5bf732d3424@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Konrad Dybcio 2024-07-29 10:42:58 +02:00 committed by Greg Kroah-Hartman
parent 973a578916
commit e885f5f1f2
1 changed files with 14 additions and 0 deletions
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14
drivers/usb/typec/mux/fsa4480.c
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@ -13,6 +13,10 @@
#include <linux/usb/typec_dp.h>
#include <linux/usb/typec_mux.h>
#define FSA4480_DEVICE_ID 0x00
#define FSA4480_DEVICE_ID_VENDOR_ID GENMASK(7, 6)
#define FSA4480_DEVICE_ID_VERSION_ID GENMASK(5, 3)
#define FSA4480_DEVICE_ID_REV_ID GENMASK(2, 0)
#define FSA4480_SWITCH_ENABLE 0x04
#define FSA4480_SWITCH_SELECT 0x05
#define FSA4480_SWITCH_STATUS1 0x07
@ -251,6 +255,7 @@ static int fsa4480_probe(struct i2c_client *client)
struct typec_switch_desc sw_desc = { };
struct typec_mux_desc mux_desc = { };
struct fsa4480 *fsa;
int val = 0;
int ret;
fsa = devm_kzalloc(dev, sizeof(*fsa), GFP_KERNEL);
@ -268,6 +273,15 @@ static int fsa4480_probe(struct i2c_client *client)
if (IS_ERR(fsa->regmap))
return dev_err_probe(dev, PTR_ERR(fsa->regmap), "failed to initialize regmap\n");
ret = regmap_read(fsa->regmap, FSA4480_DEVICE_ID, &val);
if (ret || !val)
return dev_err_probe(dev, -ENODEV, "FSA4480 not found\n");
dev_dbg(dev, "Found FSA4480 v%lu.%lu (Vendor ID = %lu)\n",
FIELD_GET(FSA4480_DEVICE_ID_VERSION_ID, val),
FIELD_GET(FSA4480_DEVICE_ID_REV_ID, val),
FIELD_GET(FSA4480_DEVICE_ID_VENDOR_ID, val));
/* Safe mode */
fsa->cur_enable = FSA4480_ENABLE_DEVICE | FSA4480_ENABLE_USB;
fsa->mode = TYPEC_STATE_SAFE;